1. Field of the Invention
The present invention relates to a three-dimensional model generating apparatus method and program, which are arranged to enable generation of a highly-accurate three-dimensional model of a subject.
2. Description of the Related Art
A lot of methods for generating a three-dimensional model of a subject from images acquired by photographing the subject have been proposed.
Particularly, in a widely-used method, three-dimensional points (herein after called as “vertices” in order to distinguish those from two-dimensional points) set on the surface of a previously-prepared standard model of a subject are associated with points on a photographed image, and corrections are made on coordinates of the vertices on the standard model in accordance with the association, thereby generating a three-dimensional model of the subject. According to this method, in the case of generation of a three-dimensional model of, e.g., a face, so long as eyes, nasal cavities, and the like, vertices on the standard model of the face are indexed, indices of vertices on the thus-generated three-dimensional model are common with those on the standard model at all times. Therefore, we can easily know a particular vertices, such as eyes or nasal cavities. That is a merit of this method using on the standard model.
One of face image model generating apparatuses mentioned, above is Japanese Patent No. 2,787,612 (pg. 2 and FIG. 2). In order to correct coordinates of vertices, this generating apparatus detects a center line of a face from an image acquired by photographing the face of a person from the front, detects a contour line of the face from the image acquired by photographing the face of the person from the side, detects points on the image corresponding to vertices on a standard model in view of the relationship between the center line and the contour line, and calculate the depths of the detected points.
Vertices on the standard model to which corresponding points are not detected are interpolated in a three-dimensional space. Therefore, depths of interpolated vertices on the thus-generated model is magnified not always accurate, thereby resulting in a failure to obtain a geometrically-accurate three-dimensional model.
As mentioned previously, according to the related art, the points on the image and the vertices on the standard model are associated with each other in the three-dimensional space. Hence, the discrepancy between the thus-generated model and the geometry of the actual subject is magnified, thereby yielding a problem of a failure to obtain a three-dimensional model of accurate geometry.
The present invention is conceived to solve the drawbacks of the related art and aims at providing a three-dimensional model generating apparatus, a three-dimensional model generating method, and a three-dimensional model generating program, which enable generation of a highly-accurate three-dimensional model of a subject.